Beyond Our Sky

Gluten-free Chocolate Sheet Cake

This chocolate cake is light and moist, and topped with a decadent frosting that is wonderful for any occasion.

I am actually not a huge chocolate person and usually prefer vanilla. But for some reason, I felt like chocolate cake this weekend. This is an adaption of my favourite gluten-free cake recipe. As usual, just a few recipe notes:

  • This is a butter-based cake recipe involving the creaming method, and is not an oil-based chocolate cake which involves the mixing of wet and dry ingredients. In this instance, I actually prefer a butter-based cake for several reasons; it produces a better texture with this blend of flours, the butter yields a more delicious flavour and this cake reminds me of the chocolate cupcakes my mum used to bake when I was young. Even though it is a butter-based cake, I do like to add just a bit of oil just to keep it tender.
  • Since the butter is at room temperature, the eggs should also be at room temperature. If you forget to take your eggs out of the fridge, it is not a big deal – the cake will turn out just as well – but it simply allows the butter and eggs to properly emulsify and avoids curdling.
  • This specific blend and ratio of flours is pivotal in achieving that light yet moist texture. It is very important for the white rice flour to be super fine.
  • The xanthan gum is also important for providing structure. In the recipe below, it only specifies 1/4 tsp, but if your xanthan gum is less fine and more grainy – increase it to 3/4 tsp.
  • For the frosting, the melted chocolate should be completely cooled before it is incorporated. If you prefer a buttercream that is less rich, simply add less melted chocolate.

Subsititions:

  • GF flour blends: I prefer to develop recipes with individual flours rather than using a store-bought GF flour blend. This is because each brand has a different mix of flours and may not necessarily work. However, if you have a store-bought GF flour that you know will work for cakes, simply replace the rice flour and starches with 135g of GF plain flour. Still add the almond meal, and xanthan gum if the blend does not contain it.
  • Dairy-free cake: To make this recipe dairy-free, simply use a dairy-free butter such as Nuttelex or Earth balance, and a dairy-free dark chocolate for the frosting.
  • Normal cake (not gluten-free): To make this cake not gluten-free, simply replace the rice flour, starches, almond meal and xanthan gum with 170g of a normal plain flour.

I hope you enjoy the recipe and let me know if you have any questions!

 

Gluten-free Chocolate Sheet Cake

Ingredients

Chocolate Cake

  • 170g unsalted butter, room temperature
  • 170g caster sugar
  • 2 tbsp neutral oil
  • 3 eggs, room temperature
  • 1/2 tsp vanilla extract
  • 53g almond meal
  • 75g white rice flour
  • 23g potato starch
  • 8g tapioca starch
  • 30g cocoa powder
  • 2 tsp baking powder
  • 1/4 tsp xanthan gum
  • 3-5 tbsp water

Chocolate Buttercream

  • 125g unsalted butter, room temperature
  • 210g icing sugar
  • 15g cocoa powder
  • 1/2 tsp vanilla extract
  • 2-4 tbsp milk
  • 70g dark chocolate (at least 70% cocoa solids), melted and cooled

Method

Chocolate Cake

  1. Preheat the oven to 170°C. Grease and line a 20 x 30cm pan with baking paper, leaving a 2cm overhang. Set aside.
  2. In the bowl of a stand mixer fitted with a paddle attachment, cream together the butter, sugar and oil on high speed until light and pale in colour, about 5 minutes. Add the eggs, one at a time, beating well in between each addition. Add the vanilla extract.
  3. In a separate bowl, combine the almond meal, rice flour, potato starch, tapioca starch, cocoa powder, baking powder and xanthan gum. Add this to the butter and sugar mixture, and mix on low speed until just combined. Add the water, and mix on medium-low speed for about 30 seconds until a smooth batter has formed.
  4. Pour the batter into the prepared pan. Bake for 25-30 minutes, or until the cake springs after being gently pressed with a fingertip. Remove from the oven, allow to cool in the pan for 20 minutes then transfer to a wire rack to cool completely.

Chocolate Buttercream

  1. In the bowl of a stand mixer fitted with a paddle attachment, beat the butter on high speed until light and pale in colour, about 5 minutes.
  2. Add the icing sugar gradually in 3 batches, mixing well in between each addition. Add the cocoa powder, and mix until combined. Add the vanilla extract and 2 tbsp of milk, and beat on high speed for a further 3-4 minutes until light and fluffy. If the frosting is too thick, simply adjust by adding a tablespoon or two of milk.
  3. On low speed, mix in the melted chocolate until just combined. Scrape down the sides of the bowl, then increase to medium speed and beat for about 15 seconds until a smooth frosting forms. If it seems to thick, fold in a few more tablespoons of milk to reach the desired consistency.
  4. To decorate: Spread the chocolate buttercream generously over the cooled cake, creating swirls if desired. Decorate with shaved chocolate or sprinkes.